1. Field of the Invention
The present invention relates to methods for the manufacture of concrete roof tiles, and more particularly to methods for the application of coloring slurries to concrete roof tiles during the manufacture of such tiles.
2. History of the Prior Art
Concrete roof tiles have enjoyed widespread acceptance and increasing popularity in recent years. Such tiles have a number of advantages over other types of roofing materials, including the fact that they are extremely durable and are noncombustible.
Concrete roof tiles are typically manufactured by the continuous extrusion of a ribbon of concrete onto a plurality of supporting molds with the ribbon being periodically cut to form the individual tiles. The tiles are then sprayed with one or more coloring slurries prior to curing of the concrete. Following curing, the hardened tiles are separated from the supporting molds and are typically stacked on wood pallets for transport to the job site where they are to be installed.
As the popularity of concrete roof tiles has increased, various different coloring schemes have evolved which provide architects, builders and roofers with a variety of different eye-pleasing effects. Whereas conventional shingles are typically finished in a single, uniform color or in a relatively simple, repeating pattern, concrete roof tiles can be manufactured with the individual tiles having as many as four, five or even more different colors so as to provide the finished roof with a variety of different, aesthetically pleasing multicolor effects. The variety of possibilities is even further enhanced by the different shapes or so-called profiles in which concrete roof tiles can be made. Most such shapes are undulating or rippling in configuration. This enables different colors to be applied to different portions of the tile, for example, so that one color will dominate when the roof is viewed when the particular angle with still other colors dominating when the roof is viewed from other angles.
Present techniques for applying multiple colors to concrete roof tiles typically utilize relatively simple repeating patterns. Those patterns which vary from one tile to the next usually repeat after just a few tiles. For example, where an overspray applicator having a scraper in conjunction with a rotating drum and a rotating cylindrical brush is used to provide overspray coloring to tiles which have been sprayed with a base coat of different color, the overspray slurry is continuously supplied by the scraper to the rotating brush for spraying onto the tiles. At the same time the scraper is continuously oscillated across a transverse path so as to move the overspray pattern back and forth across the widths of the tiles as they pass under the overspray applicator. This provides a band of the overspray or second color which undulates across the widths of the tiles in repeating, predictable fashion. Even where additional colors are used, the patterns are simple and repeat frequently.
Conventional installation techniques involving multicolor concrete roof tiles typically require the installer to pay some attention to the order in which the tiles are installed on the roof. For example, multi-color tiles of varying patterns often require hand blending. This means that the installer must hand pick the tiles from stacks thereof as the tiles are sequentially installed in rows along the roof. An experienced installer using this technique can achieve desired artistic effects while at the same time avoiding certain designs or effect which may be considered displeasing. Some types of tiles require that the installer place the tiles along the roof in a particular sequence. For example, a varying multi-color pattern which repeats with every fourth tile so as to result in four different color patterns on the individual tiles may require that the repeating sequence of four patterns be continuously repeated as the installer lays the tiles side-by-side along the roof.
Both hand blending sequential installation require considerable extra effort on the part of the installer, and above all are quite time consuming. Tile roofs can be installed in far more economical fashion if the installer can simply pick tiles at random and without regard to the manner in which the color patterns on the individual tiles may blend together to achieve a particular effect. At the same time such a random installation of tiles should provide a pleasing, attractive multi-color appearance, which appearance should be variable in order to achieve different effects.